#include<bits/stdc++.h>
using namespace std;

int main(){
    string S;
    cin >> S;
    int t=0,r=0,e=0;

    for(int i=0;i<S.size();i++){
        if(S[i]=='t') t++;
        if(S[i]=='r') r++;
        if(S[i]=='e') e++;
    }

    if(t<r && t<e/2) cout << t <<endl;
    else if(r<t && r<e/2) cout << r << endl;
    else cout << e/2 << endl;

    return 0;
}